A conventional side-by-side refrigerator typically has a manually adjustable orifice in the wall between its side-by-side food and freezer compartments. A thermostat then regulates operation of the refrigerator compressor and fan in response to change in food compartment temperature. Compressor operation rapidly cools the freezer compartment and the fan moves cool freezer air through the orifice into the food compartment until, when food compartment temperature is restored, the thermostat terminates further compressor and fan operation. With such a system, the thermostat and the orifice size are adjusted through trial and error by reference to the relative coolness or firmness of items in the food and freezer compartments and the initial settings are usually suitable for individual taste taking into account the ambient temperature and the frequency and duration of door openings by the user during the period when the settings are first made. Frequently however the settings are not then readjusted as the conditions of use gradually change and as a result, in many cases where the orifice is left too small for the new conditions for example, the compressor will operate excessively and will unduly lower freezer temperature before sufficient cool freezer air flows into the food compartment to restore its temperature and to cause the food compartment thermostat to terminate the compressor operation.
It had been proposed that thermally responsive means be used for regulating air flow from the freezer into the food compartment and that a thermostat then regulate compressor and fan operation in response to changes in freezer compartment temperature. Such a system would provide better control of the temperatures in the food and freezer compartments under changing conditions and would permit more energy efficient refrigerator operation. However thermally responsive control means having the desired operating temperatures ranges, calibration capability, selective adjustability by the user, ruggedness, long service life, and compactness for use in such an application have typically incorporated bellows or other relatively complex structures so that such thermally responsive means have tended to be too expensive for widespread adoption and use in side-by-side home refrigerators and the like.
It is an object of this invention to provide a novel and improved refrigerator control system; to provide such a system which is particularly adapted for use in regulating operation of a refrigerator having side-by-side food and freezer compartments; to provide such a system which is economically practiced to install and which is reliable, economical and energy efficient in use; to provide a thermally responsive control which is particularly adapted for use in such a refrigerator system; and to provide a compact and rugged air flow control which is adapted to be conveniently accommodated and operated in a home refrigerator or the like.